Field of the Invention
This invention relates to an improved process for the recovery of methyl ethyl ketone (MEK) from an aqueous mixture comprising MEK and ethanol (EtOH).
Description of the Related Art Including Information Disclosed Under 17 CFR 1.97 and 1.98 Various chemical processes are known which include the step of recovering ethanol (EtOH) and methyl ethyl ketone (MEK) in satisfactory yields from an aqueous mixture of the two compounds. One method of recovery which has been used is solvent extraction using a solvent which selectively extracts MEK from the aqueous mixture. Most of the MEK is removed from the solvent by fractional distillation and the solvent is recycled to the solvent extraction unit. However, a disadvantage of this method often encountered is that either the recycled solvent contains a relatively large amount of MEK resulting in a lower than desired recovery of MEK product obtained from the solvent extraction, or that a greater than desired amount of energy is expended in removing MEK from the recycled solvent in order to obtain a satisfactory yield of MEK. Thus, any improvement in the process resulting in the elimination or reduction of these disadvantages would be very valuable.
U.S. Pat. No. 2,528,761, issued Nov. 7, 1950 to Lake, et. al., discloses a process of separating an alcohol from a ketone by azeotropic distillation using an aromatic hydrocarbon or an alkyl derivative of an aromatic hydrocarbon as an azeotrope former. For example, ethyl alcohol may be separated from MEK using benzene as the azeotrope former, or a higher boiling alcohol and ketone may be separated using a xylene isomer or mixture of such isomers as the azeotrope former.
U.S. Pat. No. 3,404,186 issued Oct. 1, 1968 to Bailey, et. al., discloses a process for the recovery of EtOH and MEK from a MEK-ethyl acetate mixture comprising hydrolyzing at least a portion of the ethyl acetate, distilling the resulting hydrolysis product comprising MEK, EtOH, acetic acid (HOAc) water and unhydrolyzed ethyl acetate to obtain a residue comprising HOAc and water and a distillate comprising unhydrolyzed ethyl acetate, MEK and EtOH, subjecting the latter distillate to a second distillation to obtain a distillate comprising low-boiling impurities, unhydrolyzed ethyl acetate and a ternary azeotrope of MEK, water and EtOH, and a residue comprising MEK and EtOH, mixing the latter residue with water, and extracting MEK from the resulting aqueous mixture using a hydrocarbon such as n-pentane as extractant.
U.S. Pat. No. 5,453,166, issued Sept. 26, 1995 to Berg, teaches a method for 5 the separation of ethanol from 2-butanone (MEK) by extractive distillation using an extractive agent which may be any of the three xylene isomers.